Loans and Allowance for Loan Losses (Allowance for Loan Losses and Related Loan Balance Disaggregated on the Basis of Impairment Methodology) (Details) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Impaired loans	$ 10,096	$ 9,370
Impaired loans	140,048	145,360
Commercial [Member] | Allowance for Loan Losses [Member]
Impaired loans	6,409	6,127
All other loans	118,824	113,819
Commercial [Member] | Loans Outstanding [Member]
Impaired loans	109,712	118,532
All other loans	5,195,954	5,365,201
Personal Banking [Member] | Allowance for Loan Losses [Member]
Impaired loans	3,687	3,243
All other loans	59,118	74,349
Personal Banking [Member] | Loans Outstanding [Member]
Impaired loans	30,336	26,828
All other loans	3,737,121	3,900,421
Allowance for Loan Losses [Member]
Impaired loans	10,096	9,370
All other loans	177,942	188,168
Loans Outstanding [Member]
Impaired loans	140,048	145,360
All other loans	$ 8,933,075	$ 9,265,622